Mobile service equipment for overhead utility equipment



M. E. MITCHELL April 24, 1962 MOBILE SERVICE EQUIPMENT FOR OVERHEAD UTILITY EQUIPMENT Filed Sept. 12, l95

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linited rates Patent @fifice 3,031,027 Patented Apr. 24, 1962 3,631,027 MOBILE SERVHQE EQUEMENT FOR OVERHEAD UTILKTY EQUIPMENT Maurice E. Mitchell, Mannie, Ind, assignor to Lift-A- Loft Corporation, a corporation of Indiana Filed Sept. 12, 1952, Ser. No. 309,225 8 Claims. (Cl. 182-=-63) This invention relates to apparatus for servicing overhead utility equipment, for example, for repairing, cleaning, and maintaining street lights, and to the combination of such apparatus with a truck. The invention is an improvement of the apparatus of my co-pending application Serial No. 244,242, filed August 29, 1951.

The apparatus provided by this invention is of use and advantage for a wide variety of work. It is of special use and advantage in the problems involved in servicing, cleaning, and maintaining street lights, and an appreciation of its value may be found in relation to those problems. Such lights are carried at high elevations above the street or along the side of the street in positions which are quite inaccessible with ordinary apparatus. The street may be lined with parked cars and is usually busy with traffic. The supports for the lights usually include cables or arms against which it would be dangerous to support a ladder. At lower levels above the street there may be various obstructions, such as trolley wires and their supports, light wires, telephone wires, trees, etc. The cleaning and maintenance services normally required are usually not difficult nor time-consuming in themselves, but getting to the lights with the proper equipment and replacement lamps, and cleaning the dirty parts such as the reflectors and light globes, presents serious difiiculties. In most cases the lamps and globes must be carried by the servicernan as he climbs up and down a ladder or other equipment. With previously available equipment, the work involves a high labor cost and is slow. Ordinarily, a crew of two or three men can service only about fifty street lights per day.

The apparatus of my prior application is a considerable improvement over the previously available equipment. It provides a lift platform on a truck, and avoids much of the climbing, but it requires stopping the truck directly underneath the light. Parked cars may interfere, low-level obstructions may lie directly beneath the street light and prevent raising the lift in a proper position. lit is frequently necessary to maneuver the truck backward and forward a number of times in order to reach the proper transverse position. Moreover, its platform lift, operated by a cable, is relatively slow, and the controls provided require careful cooperation between the driver of the truck and the Serviceman who rides the platform toservice the light.

It is the object of my present invention to provide improved equipment to meet and overcome the problems exemplified by those set forth above, and to permit a small service crew to accomplish many times the work which could be accomplished with prior equipment, and to do so with less eifort. With equipment embodying the present invention, a two-man crew can service street lights, that is, clean the globes, replace the lamps, and do other incidental routine service work at a sustained average rate of thirty street lights per hour-an average rate of one each two minutes. It is a further object of the invention to provide mobile equipment which can be quickly moved from light to light in a retracted position to clear the various hazards normally present, and which can be stopped at a convenient position and at each stop will carry the Serviceman and his necessary tools, replacements, etc. to a convenient work position,

whether directly over the truck or to one side thereof,

and which upon the completion of the work will return him to the truck. It is thus an object of the invention to provide a work platform which in lowered position will support the Serviceman at the floor level of the truck, adjacent cleaning equipment housed in the truck, and will carry him from that truck-floor position both upward to the desired elevation and transversely to either side of the truck. In one apparatus embodying the present invention, the work platform moves from the floor level of the truck vertically to an elevation of 36 feet above the ground, and transversely 12 feet on either side of the truck. It is a further object of the invention to provide equipment which is less subject to interference from normal trafiic, parked cars, overhead obstructions, etc, and which may thus be moved to a suitable stopped position more quickly and conveniently, and which will carry the Serviceman to a convenient service work position quickly and will return him to the truck quickly. In the apparatus referred to above and embodying the invention, the platform moves to an elevation of 36 feet and transversely 12 feet in less than ten seconds, and returns to the truck floor level in a like short period. It is a further object of the invention to provide equipment of the type indicated in which various movements and operations of the apparatus are interlocked and interrelated, for convenience, for speed, and for safety to the crew.

In accordance with the invention, a lift mechanism is mounted on a self-propelled truck. Such equipment and combination is in some respects similar to that shown in my prior application, in that the lift platform lies in its lowermost position at the floor level of the truck, and adjacent to it the truck carries washing equipment for washing, rinsing, and drying street light globes and other glassware, so that as the Serviceman returns to the truck, bringing with him a dirty globe, he can wash it, rinse it, and put it in the drying equipment as the driver of the truck moves to the next street light, and from which position the Serviceman can readily pick up a clean globe, a suitable replacement bulb and other necessary parts so that they will be lifted with him on the platform to the work position. The apparatus of the present invention, however, provides a number of improvements and modifications over that shown in my prior application.

The lift apparatus includes a plurality of sections each vertically slidable on the other, with a platform carrier vertically slidable on the topmost lift section. The lowermost section is fixed on the truck, and the second section is raised by a hydraulic cylinder, and the several sections are so interconnected that as the second section rises each of the other sections raises with respect to its next lowermost section. The platform carried by the lift is a traversing platform having a plurality of sections which are extendable transversely of the truck, either to one side or preferably to both sides. Jack or stabilizing mechanism is also desirably provided, which can be moved into engagement with the ground at each stop to level and stabilize the truck as the lift is raised. The hydraulic system for lifting the platform includes control mechanism operable from the platform at any elevation so that the serviceman on the platform can readily control the lift movement. The traversing movement of the platform is conveniently electrical, and is desirably powered from a battery carried with the platform, and controlled by control apparatus operable by the serviceman on the platform.

The inter-relation and interlocking of the various operations of the equipment desirably includes means to lock the truck brakes as the lift mechanism is raised; and the traversing mechanism may be interlocked with the lift mechanism to prevent traversing when the plat-form is in the truck and to prevent lowering of the platform below the top of the truck when the platform is in an extended position. Desirably the battery which powers the traversing movement of the platform is interconnected to the truck-motor generator to keep that battery charged. The hydraulic system for operating the lift and the jacks desirably includes a pump driven through a power take-off from the truck, and pump operation may be interlocked with the truck drive mechanism so that that drive must be in neutral when the lift is raised.

The accompanying drawings illustrate my invention: In the drawings;

FIG. 1 is a side elevation of a truck embodying my invention, with parts broken away to show the apparatus inside the truck;

FIG. 2 is a horizontal section taken immediately beneath the roof of the truck shown in FIG. 1;

FIG. 3 is a diagrammatic side elevation, with parts separated from one another, showing the lift mechanism;

FIG. 4 is an isometric view of the upper end of the lift mechanism, showing the platform in extended position;

FIG. 5 is a rear elevation of the truck showing it in operative position in relation to a street light;

FIG. 6 is a plan view, partially in section, of the traversing platform;

FIG. 7 is a side elevation of the apparatus shown in FIG. 6;

FIG. 8 is a diagrammatic exploded view showing the drive for the traversing platform;

FIG. 9 is a vertical transverse section of the traversing platform.

FIG. 10 is a fragmental longitudinal section of the platform apparatus shown in FIG. 9;

FIG. 11 is a hydraulic circuit diagram showing a hydraulic system for operating the lift and the truck stabilizing jacks; and

FIG. 12 is an electrical diagram showing the platform traverse driving and control system.

The apparatus shown in the drawings comprises an enclosed truck 10 operable from a drivers seat 12 and having a movable top section 14 slidable forwardly to open the rear portion of the truck itself. The platform lift mechanism is fixed to the truck frame in a vertical position immediately ahead of the back wall 16 of the truck. This carries a traversing platform 20 which in normal lowered position lies substantially level with the floor 22 of the truck. Immediately ahead of the platform 20 and accessible to a serviceman standing on the platform 20 there are a series of tubs 24, 25, and 26 for washing and rinsing street light globes and other ware. Immediately above the tubs 24-26 there is a drying rack 28 to support washed globes. This has a false bottom 29 formed to provide a series of hot air nozzles 30. The conduit below the false bottom 29 is connected to a supply conduit leading from a blower and heater 32. Along the sides of the truck there are a plurality of shelves 34 to provide storage space for replacement lamps and other accessories. The space between them is open for movement of the driver of the truck so that he can pick up replacement lamps etc., from the shelves 34 and conveniently supply them to the Serviceman-on the platform 20.

At the rear, the truck is provided with a stabilizing mechanism shown as a pair of hydraulic jacks 40 whose cylinders are fixed to the truck frame 38 and whose piston rods are downwardly extendable and carry ground engaging feet 42.

The lift mechanism comprises a plurality of lift sections 50, 52, 54, 56 and a carriage 58 for the platform. The lift sections are supported on each other for vertical sliding movement with respect to each other, desirably on rollers 'interengaging flanges on the sections as shown in my prior application Serial No. 244,242. The platform carriage 58 is similarly mounted on the top section 56 for vertical sliding movement thereon. Each section comprises a pair of side members, conveniently of channel or 2 section as shown in FIG. 2, interconnected by suitable bracing as in my prior co-pending application. The lower section 50 is rigidly supported on the truck frame 38. The second section is connected at its top to the piston rod 62 of a hydraulic cylinder 60 supported on the truck frame 38. The second section 52 carries a sprocket 63 at the top and a cable or chain 64- extends from a fixed point on the bottom section 50 upward and over the sprocket 63 and down to a fixed point at the bottom of the third section 54. As the second section 52 is lifted by the hydraulic cylinder 60-62, this lifts the second section 52 and the sprocket 63 which it carries, to lift the third section 54 with respect to the rising second section 52. The fourth section 56 is similarly supported and operated by a sprocket 65 at the top of the third section 54 and chain 66 extending over that sprocket and having its ends connected to the top of the second section 52 and the bottom of the fourth section 56, so that this fourth section 56 is lifted with respect to the third section 54 as the latter rises with respect to the lower sections. Similarly, the platform carriage 58 is supported and operated by a chain 68 extending over a sprocket 67 on the fourth lift section 56 and having its ends connected respectively to the top of the third section 54 and to a low point on that carriage, so that in lowered position of the lift mechanism the platform lies at the bottom of the lowered top section 56, in the position shown in FIGS. 1 and 2; whereas in the extreme raised position, the platform lies at the top of the top section 56, in the position shown in FIGS. 4 and 5. The platform is thus moved by the lift mechanism from a lowered position level with the truck floor 22 to a raised position at the very top of the lift mechanism.

The platform structure has three floored sections which are relatively slidable on each other transversely of the truck to carry the platform 20 itself transversely of the truck to the positions shown in full and dotted lines in FIG. 4.

As shown in FIGS. 6, 7, 9, and 10, the platform mechanism comprises a lower section fixed to the lift carriage 58, and an intermediate section 102 movable longitudinally on the section 100, and a top section 104 movable longitudinally on the intermediate section 102 and which carries the platform 20. The three sections conveniently have channel-shaped side members and the outwardly extending flanges of the intermediate section 102 form rails by which it is supported on the lower section and by which it supports the upper section. The web of the side channels of the bottom section 100 are provided with a plurality of pairs of rollers 106 spaced longitudinally of those side channels and in which the lower flanges 108 of the side channels of the intermediate section are received. To hold the intermediate section 102 centered on the lower section 100 and with its flanges in engagement between the rollers 106, the lower section 100 carries a pair of rollers 110 on vertical axes and positioned to bear against the inner surface of the webs of the side channels of the intermediate section 102. For additional guidance, especially against misaligning swinging movement of the intermediate section 102 on the bottom section 100, the bottom section carries a longitudinal, upwardly open channel 112 which is engaged by one or both of a pair of rollers 114 positioned adjacent opposite ends of the intermediate section 102 at a distance from the plane of the axes of the rollers 110.

The top section 104 is similarly supported on the intermediate section. Thus, the side channels of the top section 104 carry a plurality of longitudinally spaced pairs of rollers 116 which receive and ride on the top flange 118 of the side channels of the intermediate section 102, and guide rollers 120 carried by the top section ride against the upper edge of the intermediate section side channels. The intermediate section 102 carries a longitudinal upwardly open channel 122 which receives one or both of a pair of rollers 124 carried adjacent opposite ends of the top section 104.

Suspended below this platform structure there is a motor 130 connected to a gear reduction 132 having an output sprocket 134 for a chain which extends therefrom over a pair of sprockets 135. In addition, the platform carries a battery 138 connected to drive the motor 130 under suitable control as set forth below, and connected also by an extensible cable 140 to a generator driven by the truck motor so that operation of the truck motor maintains the battery in charged condition.

FIG. 8 shows the cable or chain system by which the three sections are interlocked to maintain them in proper relationship and by which they are driven in the traverse movement of the platform. The chain 150 which threads the drive sprocket 134 and passes over the idler sprockets 136 extends outwardly therefrom to sprockets 152 at opposite ends of the bottom platform section 100, and from those sprockets 152 extends in opposite directions to fixed points 153 at opposite ends of the intermediate platform section 102. With this chain and sprocket connection, driving rotation of the driving sprocket 134 in either direction will move the intermediate platform section 102 in a corresponding direction longitudinally of the bottom platform section 100.

The top platform section 104 is interlocked and moved with respect to the bottom sections by means of a pair of chains 160 and 170. The chain 160 extends from a fixed point 163 at the right-hand end of the bottom platform section 100, longitudinally of the sections, over a sprocket 162 at the opposite or left-hand end of the intermediate platform section 102, and then longitudinally in the opposite direction to a fixed point 165 on the top section 104 at the same end of the platform structure from which that chain 160 started. Similarly and oppositely, the chain 170 extends from a fixed point 173 at the left-hand end of the bottom section 100, longitudinally of the platform structure, over a pulley sprocket 172 at the opposite end of the intermediate section 102, and then longitudinally in the opposite direction to a fixed point 175 on the top section 104 at the same end of the platform structure from which that chain 170 started.

As the intermediate section 102 is moved longitudinally by the drive chain 150, it moves the sprockets 162 and 172 with it, and this causes the top platform section 104 to move longitudinally with respect to the driven intermediate section 102 and in the same direction.

To drive the lift mechanism under the control of a serviceman on the platform, and to operate the hydraulic jacks 40, the hydraulic system shown in FIG. 11 can be used. This comprises a pump 180 driven through a releasable clutch 181 from a power take-off driven by the truck engine. This power take-off drive is desirably interrelated to the truck-propelling drive of the truck in known manner so that the power take-off is engaged only when the truck drive is disengaged. The pump has an intake pipe 182 connected to a reservoir 183, and has a pressure outlet pipe 134 leading to a lift control valve 186. A branch pipe 188 carries the pump pressure to a pair of jack-controlling valves 190. The pressure line 184- may also be connected through a pressure-responsive valve 185 to the intake pipe 182.

The lift control valve 186 has four ports, one of which communicates with the pressure pipe 184, and the opposite one 192 of which connects to the reservoir line 182. One side port 194 is connected to the bottom of the lift cylinder 60, and the opposite side port 196 is connected to the top of the lift cylinder 60. The valve is shown in closed position, with its plug 187 closing the ports 184 and 192. If it is rotated 45 in either direction from the position shown it connects the side ports respectively to the inlet and outlet ports to supply fluid under pressure to one end of the cylinder 60 and to provide a discharge passage for fluid from the other end of the cylinder 60 to the reservoir.

The control valves for the jacks 40 at opposite sides of the truck are independent and operable by separate handles. Each valve is similar to the valve 186 and is operable in both directions to establish the proper hydraulic connections to raise and lower the jacks 40. The truck is desirably provided with a level indicating device adjacent the valves 190 so that the serviceman can operate those jacks to bring the truck to a level condition. The two valves 1% are located in the truck within easy reach of a serviceman on the platform 20, as at the positions shown in FIG. I.

To control the lift valve 186, the lift mechanism has associated with it a telescoping control rod 200, (FIGS. 4 and 5 having a plurality of sections equivalent in number to the sections of the lift mechanism and respectively carried therewith. The top section 201 of the telescoping control rod is provided with a handle 202 within easy reach of the serviceman on the platform when the plat form is in centered position. Such handle moves with the platform and is accessible at all times to the serviceman. The lower end of the telescoping control rod 200 is linked both to the lift control valve 186 and to the throttle of the truck motor, so that as the valve 186 is opened, the throttle is opened to increase the speed of the truck motor and drive the hydraulic pump at a high rate. As shown diagrammatically in FIG. 11, the lower end of the telescoping control rod 200 carries a bell crank 204 having one arm 206 linked to a cam 208 whose movement in either direction actuates a control rod 210 to open the throttle. A second arm 212 on the bell crank 204- is linked to the actuating arm 214 of the lift control valve 186. As the control handle 202 is moved clockwise, its linkage causes the throttle cam 208 to open the throttle, and causes the valve control arm 214 to move counterclockwise, which establishes the hydraulic connections for actuating the lift cylinder to elevate the lift mechanism. Conversely, movement of the handle 202 counterclockwise actuates the throttle and moves the valve control arm 214 clockwise to establish the hydraulic connections for actuating the lift cylinder to lower the lift mechanism. While the weight of the lift mechanism will move that mechanism downward by gravity if the valve 186 is moved to downward position even though the pump is not being driven, I prefer to apply power to drive the lift mechanism down in order to expedite the lowering movement.

Traverse movement of the platform is desirably controlled from the platform itself as through a pushbutton switch box 220. A suitable electrical circuit, including stop switches to limit the platform movement, is shown in FIG. 12. The three platform sections 100, 102, and 104 are shown in diagrammatic side elevation. The lower platform section carries a central stop switch 222 having a control arm shown in depressed position, in which the switch is open. It is actuated by a shoe 223 carried by the intermediate platform section 102 in a position to open the switch 222 when the sections are centered. At the right-hand end of the lower platform section there is a normally closed switch 224, in a different vertical plane from that of switch 222, and in position to be opened by a shoe 225 carried by the intermediate platform 102 adjacent the opposite end thereof. At the left-hand end of the lower platform section 100 there is a normally closed stop switch 226 in a different vertical plane from the other switches and adapted to be opened by a shoe 227 carried adjacent the opposite end of the intermediate platform section 102.

The switch box 220 carries three switchesan out switch 228 for moving the platform out in either direction, and an in switch 230 for moving the platform inward from its extended position to a centered position, and a reverse or direction switch 232 which controls direction of out movement from the center position. The

7 out switch is connected in series through the two stop switches 224 and 226 to a relay control box 234. The in" switch is connected in series through the center stop switch 222 to the relay mechanism 234-. The reverse switch is connected directly to the relay.

The motor is a reversing motor, and is connected to be energized through the relay 234 in either direction depending upon the switch actuation. It is energized by the battery 138 carried with the platform, and such battery is connected by an extensible cable 140 to the generator of the truck motor. Conveniently the extensible cable is wound on a reel 141 carried by the truck at the base of the lift mechanism. The electrical connections will be clear from the following outline of the operation. As has been indicated, the reverse switch 232 controls relay mechanism which reverse the direction of motor operation in response to actuation of the out and in switches 228 and 23d. Assuming that the reverse switch 232 has been actuated to connect the motor for outward movement of the platform to the right in FIG. 12, depression of the out switch 228 will then actuate the motor in a direction to drive the sprocket 134 in FIG. 8 in a clockwise direction. This will pull the right-hand half of the cable 150 and will cause the platform to be extended to the right so long as the out switch remains depressed but subject to the stop control. As the platform reaches the limit of its extension to the right, the shoe 225 will engage the stop switch 224 to open the circuit closed by the out switch 228, and the platform will stop at the limit of its outward extension. If the in switch is now depressed, the platform will move inward toward its center position, with the movement continuing as long as the end switch 230 is depressed. When the platform reaches centered position, the shoe 223 will depress the arm of switch 222 to open that switch and open the circuit closed by the in switch 238, and the motor will be de-energized to stop the platform in centered position. Normally in working on a series of street lights, all of the street lights will be supported at one side of the street, and during the servicing of those lights the desired extension of the platform will always be in the same direction. In such case, the reversing switch 232 requires no actuation, and the in and out switches will cause movement of the platform always to the same side of the truck. When it is desired to extend the platform to the opposite side of the truck, the reversing switch is actuated, to reverse the responses which are effected by actuation of the in and out switches. After such reversal, depression of the out switch 228 will actuate the motor in a direction to extend the platform to the left in FIG. 12, and that movement will continue so long as the out switch is held depressed. As the platform reaches its extreme extended position, however, the shoe 227 will engage the stop switch 226 to break the out circuit and stop the platform in its extended position. Depression of the in switch will return the platform to centered position, and when it reaches centered position the shoe 223 will open the centering switch 222 to stop the platform in centered position.

The apparatus shown and described has been found highly effective for the service work for which it is intended, particularly for servicing a series of street lights. A crew of two men is useda truck driver and a serviceman. The serviceman rides the platform, and can stay on that platform throughout all operations for the whole series of street lights. The truck driver moves the truck from a position beneath one street light to a position below the next street light. At each stop, the serviceman actuates the jacks 49 if he deems that desirable in view of the contour of the roadway, to bring the truck to a level position. He picks up a proper globe for the street light to be serviced, and a proper replacement lamp, and such other incidental equipment as he thinks he may need. He then actuates the lift control handle 2th. to raise the platform to a proper elevation, and the platform carries him and his equipment to that elevation. He then actuates the platform by the traversing control switches to move himself and the platform transversely of the truck to a convenient working position beneath the street light. The range of his possible movement is indicated in FIG. 5, where the truck 16 is stopped on the roadway with two cars side by side between it and the curb. Despite the interference of those two cars, he can still move to a position suitable for servicing the street light 250 supported on a mast arm 251 from a pole 252 mounted on the curb. This is of course an extreme situation, but it demonstrates the flexibility and range of movement which my apparatus provides.

When the serviceman has reached the proper position for work on the street light 25-0 he does the work'necessary, for example, he removes the dirty globe, replaces the lamp and installs a clean globe. He then actuates the in button of the platform traverse control and the platform moves itself and him to a centered position. He then actuates the lift control handle 202 and returns with the platform to the floor level of the truck. Meanwhile, the truck driver has observed the next street light to be serviced and has placed in convenient position for the serviceman a new lamp for that next street light and such other incidental equipment as may be needed, and he sees that a proper globe is in position on the drying rack for the serviceman to use at the next stop.

When the serviceman has returned to the truck, he is in position immediately behind the tubs 24-26 for washing the dirty globe. As the truck driver moves the truck to the next street light, the serviceman washes the globe, rinses it, and places it in the rack 28, where it will be dried by the hot air from the blower 32.

For safety and greater convenience of operation, the workmen are desirably protected by interlocking relationships between the several parts of the apparatus. For example, the lift can not be operated until the truck drive is disengaged, and interlocking means is provided to lock the truck brakes as or before the lift mechanism is actuated. The traverse mechanism may be interlocked with the lift mechanism so that the platform can not be moved from its centered position unless the platform is at an elevation above the top of the truck, and conversely, to prevent lowering of the lift mechanism below a predetermined point if'the platform is in extended position. While the platform extension controls are under the convenient control of the serviceman on the platform, the mechanism is also provided with stop controls so that the platform can not be-extended beyond a safe position.

With previously available equipment utlility companies are normally able with one crew to clean and service about fifty street lights per day. With my equipment, a crew of two men can perform the same services at a sustained rate of about thirty street lights per houran average rate of one street light each two minutes. This tremendous increase in the cleaning rate is due substantially entirely to the advantages which are provided by the apparatus of this invention. The serviceman can rise to the desired level and move tranversely to the proper servicing position in less than ten seconds, and can return in a like short period of time. The crew is not called on to climb any ladder or scafford carrying lamps and cumbersome street light globes. The effort required of the crew is substantially reduced, and the danger of breakage is substantially reduced.

1 claim as my invention:

1. Overhead servicing equipment, comprising a truck having a floor-level work-area, an upstanding elevator assembly adjacent one end of the bed area of the truck, a

form being between the work-area and the elevator assembly and extending transversely of the truck, and traverse mechanism supporting the platform on the elevator assembly for vertical movement thereby, said traverse mechanism being operable to traverse said platform in both directions transversely of the truck across said face of the elevator assembly, whereby a Workman on said platform may move thereon directly from said lowered position of direct access to service equipment in said workarea to positions upwardly and transversely outward of the truck therefrom for direct access to overhead equipment and to the side of the truck.

2. Overhead service equipment as set forth in claim 1 with the addition of power means for elevating and for traversing said platform, and controls movable with and operable from said platform to control said elevating and traversing means.

3. In overhead service equipment comprising a truck having a floor-level work-area and an elevator assembly carried by the truck adjacent one end of its bed area with a platform carried by the elevator assembly at the face thereof toward said work-area and disposed in lowered position in worker-supporting position substantially at the bottom of the elevator assembly at the floor level of said work area and adjacent thereto in open access relation with said work area, the improvement which comprises the combination therewith of a platform carrier vertically movable on and by said elevator assembly, and a plurality of traverse sections carried by the carrier at said face of the elevator assembly, said sections being disposed transversely of the truck and being of a length not substantially greater than the width of the truck, one of said sections being formed to provide said platform, and traversing means operable to extend said platform section longitudinally of itself and transversely of the truck to a position projecting beyond the side of the truck, whereby a workman on said platform may move thereon directly from a position of direct access to service equipment at said work area both upward and transversely outward to elevated and transversely extended positions of direct access to equipment overhead and to the side of the truck, said traversing means being operable to extend the platform section beyond each side of the truck as desired, and a control operable by a serviceman on the platform for extending the platform section to both sides transversely of the truck and for returning it to centered position.

4. In overhead service equipment comprising a truck having a floor-level work-area and an elevator assembly carried by the truck adjacent one end of its bed area with a platform carried by the elevator assembly at the face thereof toward said work-area and disposed in lowered position in worker-supporting position substantially at the bottom of the elevator assembly at the floor level of said work area and adjacent thereto in open access relation with said work-area, the improvement which comprises the combination therewith of a platform carrier vertically movable on and by said elevator assembly, and a plurality of traverse sections carried by the carrier at said face of the elevator assembly, said sections being disposed transversely of the truck and being of a length not substantially greater than the Width of the truck, one of said sections being formed to provide said platform, and traversing means operable to extend said platform section longitudinally of itself and transversely of the truck to a position projecting beyond the side of the truck, whereby a workman on said platform may move thereon directly from a position of direct access to service equipment at said work area both upward and transversely outward to elevated and transversely extended positions of direct access to equipment overhead and to the side of the truck, hydraulic stabilizing means for the truck, and manually operable control means for said stabilizing means, said control means being positioned adjacent the lowered position of the platform at a point accessible to a workman on the lowered platform.

5. Overhead service equipment, comprising a truck, lift mechanism on the truck, a platform carrier lifted by the lift mechanism and having a lowered position adjacent the floor of the truck, traversing platform mechanism on said carrier, including three superimposed horizontal sections not substantially longer than the width of the truck and lying transversely thereof, said sections comprising a bottom first section, an intermediate second section, and a top third section, the top section supporting a platform and movable in both directions from centered position to extend beyond each side of the truck, a drive to traverse the second section in both said directions on the first, and means responsive to traversing movement of the second section to traverse the third in the same direction with respect to the second.

6. Overhead service equipment, comprising a truck, lift mechanism on the truck, a platform carrier lifted by the lift mechanism and having a lowered position adjacent the floor of the truck, traversing platform mechanism on said carrier, including three superimposed horizontal sections comprising a bottom first section, an intermediate second section, and an upper third section, the second and third sections being movable in both directions longitudinally of the first, a drive to traverse the second section on the first and a pair of oppositely arranged tension members each extending from a point on the first section adjacent one end of the assembly longitudinally to and around a pulley or sprocket like rotor at the opposite end of the second section and back to a fixed point on the third section adjacent said one end of the assembly, whereby longitudinal movement of the second section in each direction with respect to the first causes movement of the third with respect to the second in the same direction.

7. Overhead service equipment, comprising a truck, lift mechanism on the truck, a platform carrier lifted by the lift mechanism and having a lowered position adjacent the floor of the truck, traversing platform mechanism on said carrier, including three superimposed horizontal sections comprising a bottom first section, an intermediate second section, and an upper third section, the second and third sections being movable in both directions longitudinally of each other and of the first and being difierentially interconnected for simultaneous movement, whereby movement of the second in each direction from centered position with respect to the first causes movement of the third with respect to the second and in the same direction; and means to drive the sections in such movement.

8. Overhead service equipment, comprising a truck having a body, floor area, and side-walls, a lift mechanism carried by the truck at one end of the floor area and between the sidewalls, said lift mechanism comprising a plurality of fiat lift sections disposed in a generally face-to-face relationship with the outer section fixed to the truck and with each successive section carried at the inner face of the next outer section, a platform and carrier therefor carried by the inner section for movement thereon from and to a position at the base of the lift mechanism between the side-walls of the truck body and at which the platform is substantially at the floor level of the truck body, means for actuating said lift mechanism, and traverse mechanism supporting the platform on its carrier and operable at positions of the carrier above the side-walls of the body to traverse the platform lengthwise of itself and transversely of the truck in both directions to extended positions at either side of the truck.

References Cited in the file of this patent UNITED STATES PATENTS 470,112 Ehrentraut Mar. 1, 1892 607,265 McLean July 12., 1898 749,736 Jetley Jan. 19, 1904 (Other references on following page) 11 UNITED STATES PATENTS Lheureux Apr. 20, 1915 Christie Aug. 15, 1922 Wachowitz Sept. 5, 1933 Tamini May 29, 1934 Wagner et a1 Apr. 9, 1940 Couse Nov. 30, 1943 12 Craighead et a1 Nov. 27, 1951 Junkin July 29, 1952 Kamper Sept. 23, 1952 Wagner Mar. 24, 1953 Mitchell Apr. 2, 1957 FOREIGN PATENTS France Feb. 12, 1943 

